Chip Somodevilla/Getty Images(WASHINGTON) -- Sen.Bob Menendez (D-N.J.) suggested Thursday that he did nothing wrong when he raised concerns to federal health care officials on behalf of a Florida doctor accused of overbilling the government for millions of dollars in Medicare costs. The doctor is one of Menendez's major campaign donors.

The Washington Post reported that Menendez told officials that it was unfair to penalize Dr. Salomon Melgen since rules regarding Medicare billing were unclear. The account was provided to the Post by Menendez aides.

Still, Menendez's close ties to Melgen have sparked scrutiny in recent weeks. The Senate ethics committee is investigating two free trips he took to Melgen's residence in the Dominican Republic in 2010. He recently paid Melgen $58,000 from his personal funds to cover these trips. Menendez has also faced allegations that he solicited prostitutes during those trips, but he has vehemently denied the charges.

With regard to his intervention with federal health care officials, Menendez rejected the notion that his involvement amounted to exerting undue influence on behalf of a political ally.

"The bottom line is we raised concerns with [Centers for Medicare and Medicaid Services] over policy and over ambiguities that are difficult for medical providers to understand and to seek a clarification of that," he told a roundtable of journalists at the Capitol. "That is much different than what your question suggests."

The controversy swirling around Menendez has prompted some to wonder whether it could distract from his work in the Senate. He was recently appointed chairman of the Senate Foreign Relations Committee and is a member of a bipartisan group of eight senators drafting a comprehensive immigration reform bill.

Sen. Chuck Schumer (D-N.Y.), a member of the group, said that the New Jersey senator has not become a distraction and continues to play an integral role in the Senate.